[makomk]

Yeah, apparently this happened to a jewelry project on Kickstarter a while ago - one of the big backers turned out to have used a card without enough funds and the creator wound up on the hook for all the rewards, but without enough money to make them.

[jessaustin]

It seems like this scenario could be prevented even within the one-week pre-auth limit cited above. That is, pre-auth every donation a week before the campaign ends. The pre-auths that fail would then be subtracted from the total, and a week is long enough to either pay your credit card bill or decide that you can't contribute that much.

[chmike]

So a margin in funding to anticipate on such "bad luck" situation would be wise.